Check out the HE400, the midrange rise in THD is partially due to it being a planar with single-sided magnets. While the distortion in the HE400 is apparent if you look for it, it manifests as a mostly benign flavor in casual listening. Despite its ghastly looking graph the 400 is a terrific sounding headphone, I have no qualms recommending it to others.

HE400 is NOT a single-ended ortho design. You're confusing it with HE4.

But i guess that may have something to do with the demographic of the forum.

The demographic of this forum is actively influenced by both fanboy populism and an editorial pressure to conform to the prejudices and policy interpretations of some moderators. This results in a feedback loop whereby uncritical and uninformed content is promoted over potentially controversial views. Of course it is necessary to enforce a code of conduct and all such codes imply a curve which compromises on eliminating trolling and antisocial behavior versus content contributed in good faith. An analogy here would be the justice system, where it is understood that some convictions are false positives but it is nonetheless necessary to minimize the potential for false negatives.

To get back to the PM-1: I think Oppo is a great company that actively attends to customer concerns. Looking over impressions I am impressed that they got so close on their first outing. Any concerns brought up by impressions or measurements can be addressed by future revisions/new models. I was very critical of the Abyss in the beginning because of its exorbitant price and odd measurements, however it was much improved after the prototype and has some qualities which trounce the best headphones out there (according to my listening impressions).

These seem to have the bright midrange and neutral quality of Beyers, but they're a bassy ortho...but if I had to think of a dynamic that they're like, DT880 have plenty in common with these.

Everything you mentioned about the PM-1s sounded great, until you mentioned bright midrange. Can you please elaborate on that? Clearly brighter than a HD600 or an LCD3? Do voices sound a bit brighter than they should (as they do in the many Grados and AKGs)?

Everything you mentioned about the PM-1s sounded great, until you mentioned bright midrange. Can you please elaborate on that? Clearly brighter than a HD600 or an LCD3? Do voices sound a bit brighter than they should (as they do in the many Grados and AKGs)?

Check out the HE400, the midrange rise in THD is partially due to it being a planar with single-sided magnets. While the distortion in the HE400 is apparent if you look for it, it manifests as a mostly benign flavor in casual listening. Despite its ghastly looking graph the 400 is a terrific sounding headphone, I have no qualms recommending it to others.

Believe it or not, I have nearly photographic memory of all InnerFidelity and other sites' headphone distortion measurements. Yes, I was aware of the HE400's measurements, which was the reason why I added the qualifier, "several hundred dollars."

Assuming that they were measured precisely at 100 dB referenced at 1 kHz, there seems to be some sample variation. The distortion level of the HE-400 sample measured at Innerfidelity reaches more than 5 % well enough, whereas others do 2~3 % at most.

And the term "benign" is quite relative. The distortion products are mostly 2nd order with some 3rd order ones in narrow ranges, so they will not be perceived as being highly objectionable---we may also need to see distortion products at lower SPLs as well. Nevertheless, personally I would never buy (nor enjoy) acoustic devices, headphones or speakers, that have 5% distrotion in the critical midrange. I may do so if there are no alternatives in the price range, or if it is just $20.

A 1kHz tone at 100dB would be pretty ear splitting. That would be louder than you would ever want to listen.

That is not the main point. It is just a measurement condition in which we want to distinguish different headphones. It can be measured at lower SPLs. The InnerFidelity measurements include THD at 90 dB as well.

Nevertheless, personally I would never buy (nor enjoy) acoustic devices, headphones or speakers, that have 5% distrotion in the critical midrange. I may do so if there are no alternatives in the price range, or if it is just $20.

I'm quite sure you would enjoy the HE400 if you were unaware of its measurements. Distortion products at -30db aren't exactly the end of the world. It is quite possible for headphones to sound better than their measurements would imply, especially with various listeners with different preferences.

(on the HE400: [redacted] does show jumps in HD comparable to the innerfidelity graph, it is likely that both graphs would have an even more chaotic pattern spikes with greater resolution. I haven't seen its distortion measurements below 90db, but it is likely that around an average of ~70db [my casual listening level] the distortion would be below the threshold of audibility.)

Yeah I do recall someone making a post some days ago talking about how HE400's midrange THD is high because it is single-ended, in a discussion about HE560 being single-ended.

I corrected him, but then he made a small "edit: xxx" at the bottom of the post saying it's false information, rather than deleting / crossing out the bulk of his post.

And that would be me...

I did edit the post before reading anything else on it, realizing my mistake, but I am not a fan of deleting posts, so I added the "scratch that" comment and let the history stand (which is what I prefer). But, just to avoid any further confusion, I went back and removed the HE400 file link just now. You won't see a "." post from me.

I'm quite sure you would enjoy the HE400 if you were unaware of its measurements. Distortion products at -30db aren't exactly the end of the world. It is quite possible for headphones to sound better than their measurements would imply, especially with various listeners with different preferences.

I am a speaker DIY'er and measure linear/nonlinear distortions on a regular basis. The audibility depends. In my case, I know how different things with -30 dB versus -50 dB distortion products sound WHen listening to music. And in general we do not know if a driver's nonlinear behavior extends to lower SPL conditions until we actually measure, especially for midrange----bass is more predictable.

It's important to understand the scale that the measurements represent. 5% THD (distortion at -30dB) is not necessarily a deal breaker. It's right on the edge where it starts becoming a problem. It's better to try to get closer to 1% THD which is essentially audible transparency. But that's easier said than done with transducers.

I don't know what that has to do with the Oppos unless there are distortion measurements somewhere I missed. I'm not set up to measure distortion, but my impression from listening to them is that they are remarkably clean, especially in the vocal range and bass.